package com.thank.concurrency.samples.aqs;

import lombok.extern.slf4j.Slf4j;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;

/**
 * 演示Semaphore 每次获取1个许可
 */
@Slf4j
public class SemaphoreExample1 {

    private final static int threadCount = 20;

    public static void main(String[] args) {
        ExecutorService exec = Executors.newCachedThreadPool();
        final Semaphore semaphore = new Semaphore(3);

        for (int i = 0; i < threadCount; i++) {
            final int threadNum = i;
            exec.execute(() -> {
                try {
                    semaphore.acquire(); // 获取一个许可
                    test(threadNum); // 输出结果大致一秒三个
                    semaphore.release(); // 释放一个许可
                } catch (Exception e) {
                    log.info("exception:", e);
                }
            });
        }

        exec.shutdown();
    }

    private static void test(int threadNum) throws Exception {
        Thread.sleep(1000);
        log.info("{}", threadNum);
    }
}
